Abstract:In order to improve the accuracy of the navigation path and satisfy the safety of driving for autonomous navigation of agricultural vehicles, a method of detecting and tracking multiple moving objects was proposed based on panoramic vision. Panoramic vision possessed the advantages of non blind area detection and the improved algorithm solved the problem of the overlap in multiple moving objects tracking. Firstly, multi-vision images were acquired to stitch panoramic images, the improved kernel function algorithm based on segmented image was used to detect and track the moving object automatically and rapidly. Secondly, the particle filter algorithm based on path prediction was used to track multiple moving objects and solved the overlap problem. Compared with the traditional kernel function algorithm, experiments showed that the memory consumption was reduced by 66.8% and the algorithm speed was increased by 35.63%. Multiple moving objects detection using the particle filter algorithm based on path prediction could take averagely 0.78s to detect moving obstacles, and the success rate of moving objects tracking was increased by 39.5 percentage points under the condition of overlap in multiple moving objects.

Abstract:A kind of control system modeling and designing method for autonomous following vehicle was provided according to the relative heading angle detected by infrared sensors. The device and working principle of relative heading angle detecting device were introduced in detail. The control system modeling of the steering system driven by a stepper motor, dynamic relationship between front wheel steering angle and relative heading angle, and the corresponding control algorithm design of the whole control system were mainly discussed. The Matlab simulation results of relative heading angle control system were highly consistent with the practical running results of the control system. The autonomous following vehicle system which was modified from electric driven vehicles was tested in an orchard. During the test, the biggest lateral deviation of the tracks between the guiding vehicle and the following vehicle was 9.2cm, the average deviation was 3.3cm and the variance was 5.5cm2. The experimental results showed that the designed autonomous following vehicle system can run stably and reliably, reflected its application prospects in complex agricultural environment.

Abstract:In order to estimate apple yield in orchard automatically, a yield estimation method was presented which combined image processing and back propagation neural network (BPNN) based on the information of leaves and apples in the tree. Firstly, digital images of apple trees were acquired, including half ripe apples (the apple just turned red) and ripe apples (the apple totally turned red). The actual yield of each tree was weighted in harvest time. Secondly, the fruits and leaves on the image of apple tree were identified. Some useful parameters were extracted from data which were used as input variables, and the actual yield was set as output variable. Finally, BPNN estimation yield model was built and the fitting degrees of this model were 0.9287 and 0.9804 for the half ripe apples and ripe apples, respectively. When this model was applied on samples for yield estimation, the correlation coefficient between model and actual was 0.8766 in the half ripe ones and 0.9606 in the ripe ones. The results indicated that both the two models had good reliability and generalization performance. It concluded that the method presented has substantial potential for apple yield estimation.

Abstract:Agricultural internet of things (IOT) and sensor technology has been widely used in the informationalized and mechanized orchard. The research aimed at both constructing an automatic assistant diagnosis and a real time alerting for plant disease and insect pest. The purpose also covered to realize an unmanned pest disease monitoring and to release some human interaction in making a diagnosis. A method for pathologic image recognition diagnosis based on deep learning neural network was designed and an innovative method for updating free parameters of the network was proposed on the basis of analyzing the error propagation of the network, so called the gradient descendent with flexible momentum. Then, computer recognizing pathologic images of fruit sphere was researched into systematically, where the apple was selected as a subject. Experiment result revealed the method manifested a recall rate at 98.4%. And in parallel with several well known updating schemes based momentum, the proposal was able to obviously improve the accuracy of learning network with a flatter converging curve, at a cost of short converging time. The test upon the several popular benchmark data sets also demonstrated it could perform an effective recognition on the image pattern.

Abstract:Stripe rust and powdery mildew are two kinds of the most destructive foliar diseases in wheat grown and have a significant impact on the production of wheat. They differ in the pathogenesis and prevention, so it is necessary to distinguish and identify the two diseases, which can help to improve the development of agricultural information technology and automation. For the problem that stripe rust and powdery mildew lesions are similar in color features, as well as the shape features are not obvious, it is difficult to distinguish each disease using traditional features. However, the spots of two diseases have a significant difference in the trend of the directional distribution of the leaves of wheat. With respect to this characteristic, this paper proposed an orientation coherence feature based on the directional kernel convolution (DKC) method, and applied this feature to the identification of stripe rust and powdery mildew. In detail, the DKC method used several directional kernels to convolve with image to generate direction maps and edge maps which were used to calculate the directional distribution histogram. Then, the standard deviation of the histogram was used to describe the consistency of the directional distribution in the image and regarded as an orientation coherence feature. The orientation coherence feature could be used to describe the orientation dispersion of disease. If the orientation coherence feature of a sample was large, the disease of the sample was more likely to be stripe rust. Otherwise, it is more likely to be powdery mildew. To verify the effectiveness and the noise resistibility of proposed orientation coherence feature, two experiments were performed, and the results were compared with edge orientation histograms (EOH) based method. Firstly, the DKC and the EOH based orientation coherence feature were extracted for synthetic images with different noise levels. The results inferred that the noise had little effect on the DKC based orientation coherence feature which could best describe the directional information of noise images than traditional method. Secondly, the experiment for identification of stripe rust from powdery mildew indicated that the proposed orientation coherence feature could distinct the wheat stripe rust and powdery mildew much better than EOH based feature, and the accuracy could be up to 99%. In addition, the proposed orientation coherence feature could be treated as a new description for other plant diseases and it provides a new idea for crop recognition and detection, which is important in the field of computer vision based technology for agriculture.

Abstract:Currently expert system for plant protection has the problem of poor portability and expensiveness, so a cotton diseases and insect pest diagnosis system based on image rules was developed on the Android smartphone. Binary retrieve rules were used to construct decision tree, object oriented programming was used to encapsulate binary logic classification model, rules and appropriate photographs, consequently, knowledge represented by graphics achieved. The system has two diagnosis methods of image retrieval diagnosis and binary tree retrieval diagnosis with image rules. It featured human-computer interaction on actual image of typical characteristic facts in the field. The reasoning process was realized by visualization. The system was benefit for the agricultural production in practice with excellent features as portable, practicability, friendly interface, information of picture and data, and unlimited with networks. The diagnosis accuracy was above 95%.

Abstract:In order to reduce the risk of causing harm to the hands of cutting workers in the processing of frozen-fish, the detection and recognition methods for security protection system of cutting machine based on machine vision were proposed. With the workspace of cutting bandsaw under the surveillance of the color camera, the machine vision system divided the surveillance image into different dangerous regions according to the center position of the bandsaw image, and performed image processing on the acquired surveillance images. To overcome the variance of illuminance on the operation gloves of workers, the perceptual color feature recognition method was combined with the Gaussian mixture model to classify the perceptual color features and identify the workers gloves. The final evaluation for which different dangerous regions the workers hands had entered could be given after morphological image processing and statistics from the resulting images. And the machine vision system for security protection of meat cutting bandsaw machine was implemented in the laboratory. The experimental results showed that the proposed perceptual color feature with GMM could accurately identify the color features of the gloves under the variance of illuminance. By comparing with the HSV and CIE Lab color space, the proposed detection and recognition methods could achieve good robustness and have low image processing time cost, averaging at 39.18ms. And the proposed machine vision system could meet the needs of real-time and reliability for security protection system.

Abstract:In order to reduce the traction resistance of ditch plow system and analyze the influence of operating speed on ditch plow system, the parameters of plow surface and operating speed were studied. The EDEM model of soil-plow simulation was established. The experiment was made with traction resistance as target and plow blade angle, opening of guiding curves, starting angle of straight-line elements, maximal angle of straight-line elements and operating speed as factors. The simulation results showed that during the range of the experiment, traction resistance decreased when plow blade angle increased while it increased when opening of guiding curves, starting angle of straight-line elements, maximal angle of straight line elements increased, respectively. Traction resistance increased rapidly when operating speed increased. When operating speed ranged from 1.0m/s to 2.0m/s, traction resistance and power consumption became 1.98 times and 3.97 times bigger, respectively. The simulation optimization results indicated that under certain working conditions, when the values of plow blade angle, opening of guiding curves, starting angle of straight-line elements, maximal angle of straight-line elements were 15°, 190mm, 35° and 40° respectively, the minimal value of traction resistance was 24111N, 11.26% less than before. In order to observe the field working performance of optimized plow, the plow were printed by 3D printers and manufactured in the factory, and contrastive experiment was carried out. The results showed that compared with the former, the number of large soil block was smaller and the quality of residual soil was 62.87% less at the bottom of ditch, and the T shape of ditch was more obviously. The research conclusions could provide reference for the future optimization of ditch plow system and operating study of actual field working speed.

Abstract:In order to meet the requirements of precision planting, a soybean seedmeter was designed，which can perform operations of seed filling, seed cleaning and seed metering, achieving high efficiency, high precision and low seed damage. The optimal design of structural parameters of the seed-taking block, the key part of the seedmeter, was conducted based on the analysis of the working principle of the double-concave seedmeter, which provided a theoretical basis for the design of high-speed and high-performance planters and variable adjustment of seeding rates by adjusting the rotational speed of the seedmeter. The quadratic general rotary unitized design was carried out with the rotational speed of the seedmeter and tilting angle of the seed-cleaning ring as the experimental factors and the single seed rate as the experimental index. Based on experimental data, a mathematical model was built by using the Design-Expert software. Test results showed that the optimal tilting angle of the cleaning ring was 65°, at which the single seed rate of over 95% can be ensured when the rotational speeds were less than 110r/min.

Abstract:In order to meet the need of precision rice drilling, the rice hill seeder was designed with the air-blowing special hole and scoop-wheel based on the scoop-wheel seeder. With the optimum metering speed and optimum cleaning way, the seeding plates with four kinds of seeding holes were matched with different air-blowing pressures and air-blowing angles. The seeding tests were conducted on two kinds of hybrid rice, Peiliangyou98 andⅡyou8006. The test results indicated that the seeding performance of both two kinds of rice met the hill seeding requirements with the different seeding holes. The successful rate of hill seed number and hill distance of wavy shape hole were better than the others. The standard deviation and variation coefficient of hill distance in trapezoidal hole were better than the others. In addition, the qualified rate of hill seed number achieved above 93% and hill distance achieved above 92% under the condition of the air blowing pressure of 1～1.05kPa, and the air blowing angle of 40°～ 45°. The whole farmland experiments on prototype verified the accuracy of designed parameters for seed sowing device. The metering performance could meet the agronomic requirements of rice direct seeding.

Abstract:In order to realize the nursing seedlings of super rice, a type of vacuum-vibrating tray precision seeding device was designed. The super rice Changyou 3 was selected, the effects of relative pressure, diameter of suction hole, vibration frequency of plate, amplitude, the suction distance on seeding performance was analyzed with a five-factors and four-level orthogonal experiment. A mathematical model was established between seeding device parameters and seeding performance index, which provided the basis for the parameters selection of the precision seeder device in seeding process. The multi objective optimization genetic algorithm was made and the optimal parameters were determined as: vacuum negative pressure value of 3.68kPa, diameter of suction hole of 1.84mm, vibration frequency of 10.90Hz, amplitude of 4.09mm, the suction distance of 3.92mm which were verified by experiments. Through seeding test of the long type super rice, the results were consistent with theoretical analysis, which showed that the seeding device had a good adaptability to different varieties of super rice, which were suitable for different varieties of super rice seeding. Through sowing and seedling test, the seeding device could meet requirements of super rice planting seedling.

Abstract:According to the principle of vibrating feeder,this paper proposed a method to achieve directional transportation for corn seed. It explored the relationship between the various postures of the change process and mechanical parameters during orientation. A directional vibration test device was established by kinetic analysis while the Zheng Dan 958 corn seed was taken as the research object. The orthogonal experiment was carried out with the factors affecting the rate of directional orientation such as step height A, inclination angle of track surface B, vibration amplitude C and vibration frequency D. The test results showed that the step height A and the inclination angle of track surface B and its interaction had extremely significant effect on seed orientation. The best test combination was determined by multiple comparison analysis. The result of the forward motion directional rate from repeating ten times was 93.5% and the reverse motion directional rate was 89.4% when the altitude difference was 4mm, inclination angle was 4°, vibration frequency was 51.5Hz, and vibration amplitude was 0.18mm. The high speed photography was applied on the observation and verification for the direct and reverse motion test result, the analysis result showed that the actual state of motion was in keeping with the theoretical analysis basically.

Abstract:According to the demand of mechanized weeding in greenhouse, an intra-row weeding control system with disc-hoe was designed for electric drive weeding machine. The system, with the MC9S12DG128 binuclear MCU at its core, was composed of three Hall sensors and one rotary encoder, signals of which were real-time input into the MCU. The MCU received real-time visual signal of upper computer (PC) through RS232 serial port, and had a real-time communication with lower computer (motor drivers) via CAN bus. With the real-time control of rotation rate and rotation angle of disc-hoe, the control system realized intra-row weeding and seedling avoidance. The experimental machine included three disc-hoe units, and one land wheel on either side. Then the machine was connected to a tractor by a previa three-point suspension. The test results in greenhouse showed that the wounded seedling rate was within 10%, when the forward speed was about 1.2km/h.

Abstract:To define different effects of several concentrations pesticide for pest prevention under air assisted spraying condition, pest population decline rate and disease index were used to test effects of two kinds pesticide which were applied to pear aphids and pear black spot. Furthermore, the droplets distribution inside the canopy was also analyzed with Brilliant sulfaflavine, and the reasonable range of pesticide concentration for air-assisted spraying application was proposed. The results showed that: the amount of pesticide was 0.24L per tree, which was decreased by 33.3% compared to artificial spraying under the condition that the sprayer speed was 1m/s, the rotary speed of fan was 1200r/min, and the wind flow was 7.2L/min in one side. Compared to artificial spraying, air-assisted spraying application can achieve better control effect with the same quality of pesticides. The distribution of droplets under air-assisted condition was better than traditional way, and the amount of pesticide was suggested 1/3 that of artificial spraying, at the same time, the concentration could be increased properly in order to reach better effect, and the actual pesticide mass was suggested 1/3～1/2 that of artificial spraying.

Abstract:4ZTL-2000 rice stripper combine harvester with air suction is a feasible machine for the harvesting of super rice. Deposition chamber is a key part of combine harvester. In order to obtain the outstanding performance and optimal parameters of the deposition chamber to clean super rice, quadratic orthogonal rotational combinational design was conducted. The factors were selected as inlet airflow velocity of the deposition chamber, mass and velocity of grain fed. Cleaning rate of grain and airflow pressure drop in the deposition chamber were objective indexes. The regression models between indexes and factors were developed by using Design-Expert software. The interactions of factors on the indexes were analyzed by the response surface method. The results show that inlet airflow velocity of the deposition chamber has the most significant effect on the indexes of the chamber, followed by velocity of grain fed, then mass of grain fed. In order to make the deposition chamber reach optimum performance to clean super rice under the mass of grain fed of 3.78kg/s in combine harvester, factors in the regression mathematical models were optimized to obtain the optimal parameters as inlet airflow velocity of deposition chamber of 13.93m/s, velocity of grain fed of 18.84m/s with cleaning rate of grain out of the deposition chamber of 90.26% and airflow pressure drop in the deposition chamber of 350.36Pa. The verified experimental results were that cleaning rate of grain out of the deposition chamber of 90.1% and airflow pressure drop in the deposition chamber of 3483Pa，which were consistent with the optimized results. The results offer the information to improve the performance of the deposition chamber to clean super rice in stripper combine harvester.

Abstract:With the recent advances in sensors, electronics and computational processing power, automated technologies for combine harvesters have been made possible in part and there is an urgent need to develop a system which could monitor the clean loss in real-time. In order to monitor grain clean losses of combine harvester real-timely during the working process, distribution of grain cleaning losses on rear of cleaning sieve was studied, and the mathematical model between total losses of grain cleaning and grain volume tail on different regions was developed. The optimal mounting position of grain loss monitor sensor on combine harvester was confirmed. The experiment results showed that there was no significant impact on distribution of grain clean loss mass ratio with fan speed of 1200~1400r/min under the significance level α=0.05. The grain losses monitoring sensors, which utilizing type YT-5L piezoelectric ceramic as sensitive element, was installed on combine harvester with a vertical distance of 300mm between central line and tailing screen and a angle of 45°. Meanwhile, the grain harvesting filed test was carried out by using the mathematical model. The results showed that the established mathematical model had a good reliability, the maximum relative monitoring error of the grain cleaning loss detecting system was only 3.26%, which was relatively less than checked manually when harvested rice.

Abstract:Mechanical threshing plays an important role in the modern soybean production, which is one of key factors causing damage of soybean seeds at the same time. It can not only bring the waste of soybean seeds and economic loss, but also affect seeds germination percentages and soybean yields tremendously, especially for mechanized precision sowing technique. Facing on the problems of higher soybean damage rate and lower soybean threshing rate, the overall design and comprehensive threshing principle of double feeding rollers and combined threshing cylinder soybean breeding thresher was proposed, critical components of combined threshing cylinder, feeding device and transmission system, etc. were designed, and the prototype was developed. Combined threshing cylinder was composed of spiral arrangement of spike tooth, bow tooth, tooth and concave plate screen. The feeding device was mainly composed of double feeding roller. Pneumatic cleaning device as mainly composed of vibrating screen and fan. The main soybean varieties from Agricultural College of Shenyang Agricultural University were selected as test materials, through orthogonal experiment analysis, the three parameters: feeding gear, drum rotating speed and concave plate clearance were selected as experimental factors. Soybean threshing rate and soybean damage rate were selected as experimental indexes. The structure and working parameter of threshing performance was optimized. Experimental results indicated that feeding gear, drum rotating speed and concave plate clearance all had significant impact on soybean threshing rate and soybean damage rate. The most optimum combination region of the moisture content was 16%～18%，the feeding gear was mid gear（222r/min）, drum rotating speed was 500r/min, the concave plate clearance was 40mm, the soybean threshed rate was 98.4% and the soybean damaged rate was 1.4%.

Abstract:A detection system for rapid monitoring heavy metals in soil based on electrochemical and virtual instrument technology was developed. The ultrasonic-assistant extraction technique was used for rapid pretreatment of soil samples. Single use sensors bismuth film modified screen-printed electrodes coupled with differential pulse anodic stripping voltammetry (DPASV) provided a rapid, accurate screening system for the simultaneous determination of cadmium and lead in soil. The control program, developed in LabView, was adopted as control kernel, by combining the MSP430 microcontroller, the potentiostat circuit, I/V conversion circuit, peristaltic pump and electromagnetic valve. This system realized the automatic measurement. The probability statistics algorithms and the standard addition method were employed to overcome the inherent measurement errors existed in real soil analysis and the system detection limits were 1.8μg/L for cadmium and 2.6μg/L for lead, respectively. Experimental results showed that the system possesses many advantages such as high precision, good reproducibility, high speed and low power consumption, which was suitable for rapid evaluation and measurement of heavy metals in soil.

Abstract:In order to achieve rapid measurement of soil organic matter content, Lou soil was prepared to study soil organic matter determination method based on spectral analysis. Firstly, the soil diffusion reflectance spectrum with range of 900～1700nm was collected by using the portable spectrograph, and the abnormal samples were identified and removed to improve the accuracy. After that, based on the comparison of two different sample dividing methods, the optimal wavelengths of the modeling variables were selected by using successive projections algorithm (SPA). Then, the effect of prediction results of organic matters was analyzed with three linear modeling methods (MLR, PCR, PLS). The results indicated that PLS worked better. The RBF neural network was also built. The results of testing sets showed that the coefficient of determination and root mean square error between measured value and predicted value was 0.8019 and 0.1794 with PLS model, and 0.8281 and 0.1646 with RBF neural network, respectively. Both of them showed a high accuracy which could be used for the fast prediction of the soil organic matter content.

Abstract:The spatial prediction model of forest soil organic matter was studied based on environmental factors and mixed interpolation methods. Firstly, digital terrain and remote sensing image analysis technologies were applied to get topographic factors and index of remote sensing. Then, the correlation of soil organic matter and environmental factors was analyzed. In the end, soil organic matter was predicted spatially according to the environmental factors. Aiming at the flaw of regression Kriging (RK) which needs to compute semi-variogram, a spatial interpolation method named regression-smoothing thin plate spline (R-STPS) was presented. This two interpolation methods were applied to predict soil organic matter of Shunchang county spatially. The results showed that the prediction accuracy and computation efficiency of RK and R-STPS were almost consistent. The overall trend of spatial prediction distribution of soil organic matter of study area was similar. However, R-STPS was not needed for calculation of semi-variogram and easy to use. Therefore, R-STPS has more advantages.

Abstract:The 0-1 test method is a new binary test approach which is used for distinguishing chaotic dynamics and applying directly to time series data without the phase space reconstruction. It was proved to be an effective test after test for chaos of Chebyshev map. The 0-1 test method was used to identify the degree and spatial distribution of chaos of 83 monitoring wells with multiple timescale (5, 10, 15 and 30d) groundwater depth surveillance data series from 2001 to 2010 in Jilin city, northeast China. The results showed that multiple timescale groundwater depth surveillance data series of all monitoring wells were chaotic. The minimum K values of multiple timescale (5,10,15 and 30d) groundwater depth surveillance data were 0.9673, 0.9720, 0.9210 and 0.8863, respectively, and the maximum K values were 0.9995, 0.9996, 0.9994 and 0.9992, respectively. In addition, the spatial interpolation of their asymptotic growth rate K showed significantly spatial variability. The highest and lowest K values were mainly occurred in northern, southern part and central urban areas of Jilin city, respectively. The chaos characteristic of groundwater level was influenced by hydrology, meteorology, geology and so on. The findings demonstrated that the 0-1 test method was effective and reliable by using chaotic inspection of the Chebyshev maps and it can be very useful for reflecting the degree of chaos which had a better guiding role for the forecast of groundwater level.

Abstract:The concentrations of Cd, Cr, Cu, Pb, Zn in soil, wheat and vegetable samples from sewage irrigated farmland in Xi’an, Shaanxi Province, were determined. Results indicated that average contents of Cd and Pb in the research area were higher than soil background values in Xi’an and Shaanxi Province, respectively, and the average contents of Cu and Zn were higher than soil background values in Shaanxi Province, respectively. Significantly positive correlation was found between Cd and Pb in soils, while highly significant positive correlation was found among Cr, Cu and Zn, respectively. The principal component analysis showed Cd and Pb in soils were associated with anthropogenic activities, whereas Cr, Cu and Zn were predominantly controlled by parent material. The quality of soils were evaluated with potential ecological risk index and Nemerow pollution index, however, both of the results showed that Cd was the major pollution element in soil. In the study areas, exceeding rates of Cr and Pb in wheat samples were up to 70.00% and 80.00%, respectively; exceeding rates of Cd, Cr, Pb in fruit vegetable samples were 66.67%,100% and 66.67%, respectively; and exceeding rates of Cd, Cr, Pb in flower and leaf vegetables samples were 100%. Therefore, it was suggested that farmers should avoid cultivating high transfer factor plants, such as flower and leaf vegetables, meanwhile, sewage with Cd must be purified strictly before irrigation.

Abstract:Aiming at the problem that the concentration detection of Azotobacter chroococcum in microbial fertilizer suffers from time consuming and low automation level, a detecting method of Azotobacter chroococcum concentration based on microfluidic chip was proposed．A dedicated microfluidic chip with automatic sample injecting, dilution and cyclic voltammetry detection was designed, and the experiment platform based on microfluidic detection system was bulit. The optimum scan rate and feed rate of concentration detection in the microfluidic detection system were determined, and the performance index of the system was experimentally verified. Experiment results showed that, compared with plate counting method, the proposed method met the requirement of microbial fertilizer detection and realized rapid detection with increased automation.

Abstract:In order to study transport and distribution characteristics of soil salinity under indirect subsurface drip irrigation, a field experiment was designed to analyze salt distribution characteristics and the effect of water conducting device diameter (50, 75, 90mm) and irrigation quantity (9, 13, 17L/plant per time) on salt transportation in jujube root zone under indirect subsurface drip irrigation. The results showed that soil salt content of 10~40cm soil layer was relatively low, and soil salt content of 0~10cm soil layer was the highest in vertical direction, while soil salt content of each soil layer showed a increasing trend with the increase of distance from the outlet in horizontal direction under treatments after a period of time. After a single irrigation, desalination rate of each soil layer increased with the increase of irrigation quantity under a certain water-conducting device diameter. Desalination rate decreased with the increase of water-conducting device diameter in 10~40cm soil layer under a certain irrigation quantity, while desalination rates in 0~10cm and 40~50cm soil layer had a trend of “low-high-low” with the increase of water-conducting device diameter. Soil salt content in 0~50cm soil layer was relatively low when water-conducting device diameter was 75mm, irrigation quantity was respectively 13 and 17L/plant from July to September, while soil salt content varied little. As a result, water-conducting device diameter was 75mm, and irrigation quantity was 13L/pant, which was the suitable treatment that determined with consideration of the factors of water-saving and restraining salt. The research results had a theoretical support for the water-salt regulation and reasonable irrigation schedule in jujube field in southern Xinjiang.

Abstract:The research progresses in conversion of all-components of biomass to high-valued hydrocarbons (gasoline and jet fuel) were summarized. In the upgrading of bio-oil, the research progress for olefins and aromatics production via catalytic cracking of bio-oil and hydrocarbon fuels production via hydrodeoxygenation of bio-oil were introduced. In the use of carbohydrate, the process routes and technical principles for the synthesis of C5/C6 and C8~C15 alkanes from cellulose and hemicelluloses via hydrolysis monosaccharide were introduced, and typical catalysts were enumerated. In the use of lignin, the new progress for production of single ring phenolic compounds from lignin via catalytic depolymerization and the production of hydrocarbon fuels from single ring phenolics via hydrodeoxygenation were introduced. Meanwhile, the existing problems in the process of catalytic conversion were pointed out. For example, large amounts of H2 were needed for the production of hydrocarbon fuels from biomass. This would increase the cost of hydrocarbon fuel due to the high price of H2. In addition, catalyst used in the process of biomass-refining usually deactivates rapidly since that the formation of coke. So, it is important to make the reaction conditions mild to avoid the formation of coke, extending the life time of the catalyst.

Abstract:Hydrothermal treatment (HTT) is a promising process for conversing lignocellulosic biomass into solid fuel with higher carbon content. To investigate humification and carbonization characteristic of solid products from biomass HTT, the hydrothermal experiments were carried out in an autoclave using wheat-straw as raw materials at temperature 220℃. The residence time were set as 30, 60, 90, 120 and 180min, respectively. The micro-structure and chemical composition of solid products were analyzed by using X-ray diffraction (XRD) and Fourier transform infrared (FTIR). The experimental results showed that the carbon content in the solid increased from 45.86% for 30 min to 49.06% for 180min. There was a strong peak in the diffraction angle 2θ of 26° in the XRD spectrum at residence time 60min. The microcrystalline structure of the solid approached to that of graphite. With the residence time increasing, the degree of aromatization and carbonization increased. The solid products contained numerous humus, had plenty of aromatic structure and oxygen functional groups. Longer residence time was favorable for raising the extent of carbonization of solid products during biomass HTT. The research results provided a data reference for the fundamental process control and improvements of hydrothermal carbonization of biomass.

Abstract:The removal of CO2 with aqueous alkanolamine solutions is an important research direction in the field of biogas purification technology, and the research on the kinetics and mass transfer performance of the CO2 absorption is the mainly theoretical basis of optimizing biogas purification process. In the process of using monoethanolamine (MEA) aqueous solution, the Hatta number Ha, enhancement factor E and volumetric overall mass transfer coefficient KGae were studied experimentally at various reaction conditions, such as MEA concentration, gas flow rate, CO2 concentration, and absorption temperature. Furthermore, the impact on the mass transfer performance of reaction and the premise of applying the pseudo first order reaction were also analyzed. The results show that the values of Ha, E and KGae increase with increasing MEA concentration but decrease with increasing CO2 concentration. When the gas flow rate is increased, Ha and E decrease, while KGae initially increase and then decrease. The above parameters increase with increasing absorption temperature, and KGae gradually decrease when the temperature is higher than 57.4℃. Under the experimental conditions, only when the absorbent concentration is higher than 2.5mol/L or the gas flow rate is lower than 5.73kmol/(m2·h), the reaction of MEA and CO2 can be described as a pseudo-first-order reaction. The results can provide a reference for the optimization and development of biogas purification technology.

Abstract:The study aimed to investigate the effects of exogenous microorganisms on fermentation efficiency of Sophora flavescens branches for substrate production. The randomized block design was used with dried chicken manure as the nitrogen source. The effects of exogenous microorganisms on fermentation performance parameters of Sophora flavescens branches in substrate production were studied. The results showed that the vaccination crude fiber degrading bacteria inoculation and cellulose enzyme preparation, which had a persistent high temperature (higher than 50℃ and reached to 5d) and a shorter body decomposition time of Sophora flavescens, had a significant temperature increasing speed which faster than CK. At the end of the pile, for the vaccination crude fiber degrading bacteria inoculation and cellulose enzyme preparation, the TOC decreased by 8.52% and 8.01%, C/N ratio decreased by 5.35% and 5.00%, content of cellulose decreased by 3.31% and 3.29%, degradation rate of hemicellulose decreased by 2.89% and 2.93%, lignin content decreased by 2.01% and 1.98%, total nitrogen increased by 16.1% and 18.2%, total phosphorus increased by 18.5% and 19.0%, total potassium increased by 49.1% and 48.1%, respectively, which accelerated the decomposition of organic matter and cellulose, improved the content of total nitrogen, total phosphorus and total potassium and ensured the fertility after maturity. Moreover, with the vaccination crude fiber degrading bacteria inoculation and cellulose enzyme preparation, the pile density increased by 6.10% and 9.20%, the total porosity increased by 9.28% and 9.90%, the water holding porosity increased by 4.83% and 6.09%, respectively. After the maturity, the physical and chemical indicators were in line with the requirements of an ideal matrix. The germination index (GI) of cabbage and cucumber seed were up to more than 85%, eliminating the toxic effects of Sophora decomposing products effectively. There was no significant difference between the performance parameters of vaccination crude fiber degrading bacteria inoculation and cellulose enzyme preparation. Considering the demanding of fermentation temperature, decomposition cycle, crop protected plant root growth and fixed function of the physicochemical properties, the vaccination crude fiber degrading bacteria inoculation and cellulose enzyme preparation had a good promoting effect on Sophora flavescens substrate.

Abstract:Taken biohythane residue of straw as materials, the granulation technology and fertilizer characterization of organic-inorganic granular-fertilizers were studied. The straw residue contained abundant materials such as lignin and cellulose, as well as poor viscosity. It needs to be added to the binder to increase the rate of grain of granular-fertilizers, instead of to be produced directly. While bentonite processed a wide source, low cost, excellent viscosity and expansibility, which could be used as a good soil conditioner. Besides, polyacrylamide (PAM) was a high viscosity water-soluble polymer, which could be used widely. In order to improve the physicochemical property of biohythane residue and reduce the cost of granular-fertilizer, these two binders were used to develop the granular experiment under the content of organic and nutrient for 18 formulas, which belonged to four groups. Though the comparisons of particle size, compressive strength, content of organic and total nutrient, pipe particles, water absorption, water retention and expansion, the technology and formula was optimized. The results showed that the range of particle size and compressive strength of biohythane residue respectively were（3.16±0.15）~（4.39±0.36）mm, and（6.82±0.59）~（42.95±4.78）N. Using the bentonite PAM composite binder, T3 group, of which the content of organic and total nutrient could respectively reach up to 28.86% and 15.40%, can meet the requirement of national organic inorganic fertilizer type Ⅰ. T32 showed the best capacity of water retention among T3 group, and the water absorption, water retention, expansion rate achieved to 128%, 50% and 10.02%, respectively.

Abstract:Meat is one of the most important foods in people’s daily life, its quality affects our health directly. In recent years, the adulteration incident of water-injected meat continues to occur. The safety issue of meat food has attracted the social attention, so the research of water-injected meat technology is necessary. The traditional inspection methods of water-injected meat were discussed and their disadvantages were analyzed. The nondestructive detection technology was a dominant means for water-injected meat quality detection and supervision system. Then authors summarized the research status and characteristics of four nondestructive testing methods (bioelectrical impedance, nuclear magnetic resonance, ultrasonic technology and near-infrared (NIR) spectroscopy) for moisture content of meat. The application of NIR spectroscopy technique for moisture content detection was specially described. The review indicated that NIR was an effective technique to detect moisture content of meat for it was more sensitive to water. The discussion also focused on future work to improve NIR ability to predict water-injected meat. In conclusion, the paper shows that NIR has a considerable potential to predict water-injected meat quality criteria.

Abstract:The effect of preservation technologies on table grape was systematically analyzed and effect of six preservation technologies and controlled freezing point storage was comprehensively compared and evaluated in the aspect of three indicators of the loss of table grape, i.e., berry shatter, rotting rate and weight loss based on multiple regression. The evaluation results showed that controlled atmosphere storage, preservative film, 1-MCP, SO2 fumigation, the fresh-keeping agent CT2 and simplified packet and controlled freezing-point storage can effectively reduce the loss of the fruit. The influence of controlled atmosphere storage, SO2 and controlled freezing-point storage was more obvious in decreasing the three indicators of the loss of table grape. Controlled atmosphere storage and two fresh-keeping agents’ impacts on the rate of rotting and weight loss of table grape were enhanced with the course of time. In addition, the loss of fruit would be increased by using overdose of fresh-keeping agents, while the preservatives on the fruit can be enhanced by SO2. The preservation performance of preservative film would be seen gradually over time but the effect was very weak; 1-MCP has few performance on fruit preservation but it can achieve better performance in rotting rate control of table grape.

Abstract:Aiming at the problem of multi-objective design for refrigerated compartment, an optimal design model of refrigerated compartment was established. The actual constraints of compartment heat transfer, compartment seal, respiratory heat of goods within the refrigerated compartment and its main design parameters were comprehensively considered. The smallest heat transfer coefficient and maximum internal space of compartment were selected as objective function. Parameters of the refrigerated compartment were optimized with Matlab software, and the compartment heat transfer coefficient and the best thickness of compartment insulation material under different parameters were analyzed. Results showed that the optimized design method was suitable for insulated compartment of refrigerated trucks. The optimized heat transfer coefficient and the smallest thickness of compartment insulation material were different under different conditions. When truck speed was zero and the thermal conductivities of compartment insulation material were 0.007, 0.023, 0.030, 0.042, 0.045W/(m·K), and the conditions of optimal compartment heat transfer coefficient and the largest internal space of compartment were satisfied simultaneously, the corresponding optimal thicknesses of compartment insulation material were 0.07, 0.14, 0.16, 0.19, 0.20m, and the heat transfer coefficients were 0.0985, 0.1603, 0.1823, 0.2139, 0.2176W/(m2·K), respectively. The thickness of compartment insulation material decreased and compartment heat transfer coefficient increased with the increase of truck speed. In addition, there was a positive correlation between the smallest thickness of compartment insulation material and the optimal heat transfer coefficient.

Abstract:Many linear or non-linear statistics models have been developed for the estimation of fractional vegetation coverage by using vegetation indices. However, as the disturbance by uncertainty factors such as various crop planting density and nitrogen application, vegetation indices are limited to monitor regional vegetation coverage. In this paper, vegetation indices inversion models of fraction vegetation coverage based on regression analysis method were established and evaluated by using observed hyperspectral reflectance and vegetation coverage data set of winter wheat in the year 2010—2011. Firstly, the empirical models’ applicability (sensitivity, interannual stability and accuracy) were analyzed by using noise equivalent and model evaluation parameters. Simulation results indicated that there is a better result of using a second order polynomial regression equation to describe relationships between vegetation indices NDVI (Normalized difference vegetation index), TSAVI (Transformed soil adjusted vegetation index) and fraction vegetation coverage. While vegetation indices MSAVI (Modified soil adjustment vegetation index) and EVI (Enhanced vegetation index) exhibited a linear relationship with various fraction vegetation coverage. Evaluation results showed that: the correlation coefficient of regressed evaluation equations between predicted and measured vegetation coverage (Fc) were a little lower than the former modeling equations. All the evaluation relationships were significant at p=001 confidence level, which indicated these vegetation indices inversion models seemed stable among years and could give simple but reliable estimate of fraction vegetation coverage in this region. Sensitivity analysis suggested that under low to medium coverage (0~60% Fc) conditions, if the local soil information was available, using TSAVI to estimate variation of vegetation coverage showed better performance. However, if there was no information on soil characteristics, NDVI could assure estimation accuracy of fraction vegetation coverage. When vegetation cover Fc>60%, MSAVI was suggested to be used for estimating vegetation coverage, which displayed better sensitivity, stability and accuracy. Then, the general linear model (GLM) was employed to analyze the residuals of empirical models under conditions of various planting densities and nitrogen application rates. The results were somewhat inspiring: under condition of adequate water supply, all four vegetation indices (NDVI, EVI, TSAVI, MSAVI) exhibited no sensitive to various planting densities and nitrogen application rates during the entire growth period of winter wheat. This means models based on these four vegetation indices may not require re parameterization when apply to crops with different planting densities and nitrogen application rates. The regional winter wheat coverage could be directly estimated by using vegetation indices inversion models under the circumstances of abundant water supply. These findings provide a theoretical and technical support for the use of vegetation index to quickly and accurately estimate the regional vegetation coverage. However, as the regional land surface could be various and changeable, this paper could only explain the strength of vegetation indices inversion models for adequate water supply conditions, further studies are required for assessing vegetation indices method applicability in different crop intercropped and water and fertilizer coupling conditions.

Abstract:Data assimilation method combines with remotely sensed data and crop growth model has become an important hotspot in crop yield forecasting. PyWOFOST model and remotely sensed LAI were respectively selected as the crop growth model and observations to construct a regional winter wheat yield forecasting scheme with EnKF algorithm. To eliminate cloud contamination, a Savitzky-Golay (S-G) filtering algorithm was applied to the MODIS LAI products to obtain filtered LAIs. Regression models between field-measured LAI and Landsat TM vegetation indices were established and multi-temporal TM LAIs was derived. The TM LAI with time series of MODIS LAI was integrated to generate scale-adjusted LAI. Compared the assimilation accuracy using these three different spatio-temporal resolution remotely sensed data, validation results demonstrated that assimilating the scale-adjusted LAI achieved the best prediction accuracy, in potential mode, the determination coefficient (R2) increased from 0.24 which without assimilation to 0.47 and RMSE decreased from 602kg/hm2 to 478kg/hm2 at county level compared to the official statistical yield data. Our results indicated that the scale adjustment between remotely sensed observation and crop model greatly improved the accuracy of winter wheat yield forecasting. The assimilation of remotely sensed data into crop growth model with EnKF can provide a reliable approach for regional crop yield estimation.

Abstract:A leaf area index simulation model of cotton was developed under full and deficit irrigation in Xinjiang. The model was based on beta function of daily heat effect as time scales, and the effect of soil water stress was considered. One ordered derivative of the Logistic function was used to describe the changing rate of leaf area index. One ordered derivative of the Logistic function was also used to describe leaf senescence process and assumed that leaf senescence occurred since the early flowering. The acceleration effects of soil water stress and temperature on leaf senescence were also considered in the model. Finally field observations from Shihezi were used for model parameter calibration, evaluation and sensitivity analysis. Evaluation results showed that under the condition of full irrigation the root mean square error (RMSE) between simulated and observed leaf area index (LAI) values was 0.22m2/m2 and the residual accumulation coefficient (CRM) was -0.01. Under the condition of 20% and 40% deficit irrigation RMSE and CRM were 0.37m2/m2, 0.05 and 0.05m2/m2, 0, respectively. In addition, the determination coefficient of linear relationship between simulated and observed LAI was 0.96. Simulation results showed that the model was accurate in describing the dynamic changing process of cotton LAI during the whole growth period in Xinjiang. Sensitivity analysis results showed that under the condition of sufficient water, potential leaf aging area, maximum daily leaf extension area and aging area, early flowering start time were the main parameters affecting the model. The model had a few parameters and it can be used to supply the LAI dynamic information for establishing the Xinjiang cotton growth model and evapotranspiration model.

Abstract:As one of the machine learning algorithms, random forest (RF) regression was proposed firstly to construct remote sensing monitoring model to inverse leaf SPAD value in different growth stages of wheat. The experiment was carried out during 2010—2013 in Jiangsu province. Based on the wheat leaves and synchronous China’s domestic HJ-CCD multi-spectral data in the jointing stage, the booting stage and the anthesis stage respectively, the relationships between SPAD and eight vegetation indices were analyzed at corresponding period. According to the selected vegetation indices which were significantly related to the leaf SPAD value in the 0.01 level, the model for estimating leaf SPAD value at each period was built by using RF algorithm, namely the RF-SPAD model. At the corresponding period, SVR-SPAD model which was based on the support vector regression (SVR) and BP-SPAD model which was based on the back propagation (BP) neural network were constructed as compared models. SVR and BP neural network were both machine learning algorithms. Based on R2 and RMSE, the learning abilities and generalization abilities of three models at each period were analyzed. The results showed that the RF-SPAD model at three stages presented the strongest learning ability, which its R2 was the highest as well as RMSE was the lowest, concretely, R2 and RMSE were 0.89 and 1.54 in jointing stage, 0.85 and 1.49 in booting stage and 0.80 and 1.71 in anthesis stage respectively. RF-SPAD model’s prediction ability was equal to or higher than the reference models which R2 and RMSE were 0.55 and 2.11 in jointing stage, 0.72 and 2.20 in booting stage, 0.60 and 3.16 in anthesis stage respectively.

Abstract:With the help of semantic processing of keyword in semantic retrieval technology, a mobile terminal-oriented text to speech system was designed for agriculture knowledge. The ambiguous phrase encountered in text segmentation were cutting by using semantic search technology which could converted agricultural text knowledge to smooth and natural voice, and popularized agricultural knowledge combining call center and mobile terminal technology. Firstly, the text analysis flow was analyzed, and the ambiguous phrase which was the key point of text to speech processing was confirmed. Based on this key point, the word segmentation dictionary was designed, and the ambiguous phrase was extracted based on the dictionary matching and statistical analysis. Secondly, the ambiguous phrase was processed based on semantic retrieval and the segmentation of ambiguous phrase was realized. Finally, the functions of speech synthesis and prosodic processing were realized with the software of Cool Edit Pro 2.0, and mobile terminal-oriented text to speech system was developed for agriculture knowledge which could effectively solve the problem of ambiguous phrase processing.

Abstract:With the development of remote sensing technology, monitoring and dynamic analysis of ponds is becoming easier to obtain which is very important for regional LUCC research and water resource protection. Taking Honghu city in Jianghan plain as study area, the multi-scale segmentation was carried out based on object-oriented method according to the Landsat TM remote sensing data in 1990, 2000 and 2009. The spectral, space, texture features were used as well as the expert system was also combined for the extraction of ponds information. Remote sensing monitoring and spatial-temporal evolution analysis were carried out on the change of pond in Honghu city. The results showed that ponds area performed an increasing trend in the past 20 years. The increased ponds area in 1990—2000 and 2000—2009 were 306.53km2 and 379.69km2, respectively. The increasing pond area decreased with increasing distance to lakes, and the increasing pond area usually changed from farm land, lakes and rivers. Object-oriented ponds information provides important reference data in monitoring region environment and resources.

Abstract:Applying the good nonlinear classification ability of the least squares support vector machine (SVM) algorithm, this paper conduced the classification of land use in agricultural district from the high-spatial resolution ZY1-02C remote sensing images, which was based on the SVM method integrating information of shape and texture. It shows that the high-spatial resolution ZY1-02C data can realize land classification quickly and effectively, and the classification accuracy is increased by adding the feature information. The least squares SVM classification results were ideal, the overall accuracy was 82.53%, and the Kappa coefficient was 0.8071. It has higher accuracy than traditional method and provides a feasible method for the classification of land use based on domestic high-spatial resolution satellite.

Abstract:Cyber-physical systems have strict real-time and space constraints, and event driven is one of its important characteristics. In CPS, events are composed of the change of the physical environment and object state, which form the closed-loop process of events trigger, perception, decision-making, control, then to events, and ultimately change the physical state of the object. This paper outlines some preliminary exploration of spatial-temporal event model of CPS, and then make a further study. According to CPS’ event-driven nature, spatial-temporal event model was described from time, space and observer, and established for major components of CPS based on the characteristics of precision agriculture (PA): the physical world, sensors, calculation (control) unit, actuators, and timer. Finally established spatial-temporal event model was validated by closed-loop process of sprinkler incident in precision agriculture, and it was proved that these events model can be used in PA. It turns out that spatial-temporal events in precision agriculture CPS are preliminarily discussed which lays the foundation for future research on event model applied to PA.

Abstract:In traditional forestry works, the compilation of volume tables by cutting down trees and using analytic timber volume estimations is faced of problems such as large destruction, high costs and low efficiency. Therefore, an estimation method was proposed. First, diameter at breast height and ground diameter were manually measured. Then, the horizontal angles and zenith distances at corresponding trunk positions of live standing trees were measured by using the approximate division of analytic timber based on an electronic theodolite. Finally, the timber volume was estimated by simulating mean sectional division volume as per summation of conical frustum. The measured data of standing timber volumes from poplar in Beijing were used as true data for examination. The errors of timber measurement from electronic theodolites were theoretically analyzed according to error propagation laws. Based on the four grades of electronic theodolite precision classification in China: Ⅰ(DJ-1), Ⅱ(DJ-2), Ⅲ(DJ-6) and Ⅳ(DJ-15), the errors and the limit errors of root mean square error (RMSE) during measurements of tree height and timber volume were computed. Moreover, the differences and applicability of electronic theodolites with different precision levels were analyzed. The results showed that because of error propagation and accumulation, the errors of timber volumes measured by electronic theodolites with the same precision were larger than the errors of tree height. When timbers with different sizes were measured by electronic theodolites of the same precision level, the errors slightly changed along with the size of timbers. With the increased standard deviation in angle measurements by electronic theodolites, the errors in forest measurement also increased. When the standard deviation of electronic theodolites was ±0.5″, the RMSEs in measurements of tree height and timber volume were ±6.5500×10-2m and ±1.474×10-3m3, respectively, while the relative errors were 0.44% and 0.73%, respectively. When the standard deviation of electronic theodolites was ±15.0″, the RMSEs in measurements of tree height and timber volume were ±8.9275×10-2m and ±4.385×10-3m3, respectively, while the relative errors were 0.60% and 2.14%, respectively. Therefore, the existing Ⅰ～Ⅳ electronic theodolites applied into tree measurements all conform to the precision requirement that relative errors do not exceed 3%～5%, and satisfy the requirements of different forestry works.

Abstract:Upper diameter data is difficult to obtain and the trunk segment boundaries are difficult to determine accurately by using traditional stem form index research method. To solve the above problems, a method based on stumpage non destructive accurate measurement technique by using the electronic theodolite was proposed. 198 larches were selected as samples and each one was divided into ten equal segments. Relative stem shape index of all segments were calculated. Firstly, significant differences between those relative segments were found by using variance analysis method. Subsequently, a tree could be aggregated with 2~10 trunk segments by using cluster analysis. In order to acquire the optimal quantity of segments for volume calculation, all statistical combination was tested by comparison of relative stem form index and volumes observed using electronic theodolites. The results showed that the optimal quantity of segment was obtained when the stem was divided into three segments, average relative stem form indexes for each segment (corresponding to height) were: 4.295（H0.0~H0.1）,1.524（H0.1~H0.4）,1.670（H0.4~H1.0），where H is the total height of a tree. Those parameters could be quantitatively described as trunk-shaped boundary. Thus a tree volume could be accurately measured by just measuring diameters at the corresponding height, which could effectively reduce the labor consumption on field survey and related researches.

Abstract:Among the various factors affecting the variation of plant stem diameter, meteorological conditions and soil water content are very important ones，besides natural growth. Soil water content together with four main meteorological parameters in greenhouse, including air temperature, relative humidity, pressure and photosynthetically active radiation, were selected for observing with four sunflower samples and two tomato samples at late stage of growth. Using part of the data measured from one sunflower sample, the principal component analysis was performed to set up a regression model. Data from sunflower samples and tomato samples were input to the model to predict the stem diameter variations of the sunflower samples and tomato samples and compared with the observed stem diameter variations. Comparison results showed that the regression model had a good prediction for the dynamics of stem diameter variations in sunflowers and tomatoes at late growth stage. The coefficients of determination in correlation analysis were above 0.6 and reached 0.649~0.782, while the root mean square errors were 0.029~0.143.

Abstract:Adaptive optimal kernel (AOK) and Hilbert-Huang transform (HHT) marginal spectrum methods were introduced to process acoustic signals from effervescent atomizer. The time-frequency results reflected the information of bubble pressure, bubble size and gas liquid mass ratio fluctuation which had significant impacts on spray. The experimental results showed that the outflow moment of bubble could be accurately captured by AOK time-frequency spectrum, and the pulsation of amplitude could reflect the gas-liquid mass ratio fluctuation. The Hilbert marginal spectrum power was concentrated in a short frequency range. The power-frequency distribution was affected by gas-liquid pressure and gas-liquid mixture form. The Hilbert marginal spectrum power was symmetric with the center frequency which was positively correlated with bubble pressure, but little correlated with bubble size. Time-frequency analysis of acoustic signals from effervescent atomizer provides a new tactics for further study of the mechanism for effervescent atomization.

Abstract:A small scale ceramic tube was used as a combustor nozzle, and a coaxial jet ethanol flame was established in the confined space between the ceramic tube and the quartz glass tube. The fuel flow rates were 0 ~ 2.1mL/h, and the ceramic tubes with inner diameters of 1.0mm and 0.6mm. The small jet flame characteristics were analyzed, while some relevant characteristic parameters were discussed. Some important parameters were selected, including high temperature droplet evaporation rate, normalized heat loss, and quenching diameter. Based on these, the effects of the fuel flow rate and the nozzle inner diameter on flame characteristics, including stabilities, flame temperature and flame shape, in the confined space were investigated experimentally and numerically. When the liquid ethanol flow increased from zero, the change process went through five stages and the flame temperature increased. When the burner nozzle diameter was reduced, the flame became smaller. The results showed that fuel flow and nozzle diameter played an important role in fuel evaporation and combustion process. In the stable combustion stage, overall fuel evaporation, flame temperature and height all increase with the increasing of the fuel flow rate, resulting in flame ignition difficulty in low flow rate and flame oscillation in high flow rate. Normalized heat loss increases, flame temperature and height both decrease due to the diminishment of the nozzle diameter and it would affect the flame stability. Properly adjusting the fuel flow rate and the burner nozzle diameter is helpful to enhance the flame stability.

Abstract:The calculation model of rotary engine was established. Combined with the self-made program in CFD software, a 2-D dynamic simulation of the combustion process of the rotary engine was made and verified by using the experiment results. On this basis, the evolution process of combustion in direct injection LPG engine was obtained, the combustion characteristic of the engine with the three representative positions of nozzle were analyzed and the best installation position of nozzle was determined. Then a further study was conducted on the effect of the injection time and injection duration on combustion process in the rotary engine with the optimal installation position of the nozzle. The results showed that in a given speed, fuel injection direction, injection speed, injection duration and spray cone angle, the engine had a best injection advance angle that could lead to a reasonable distribution of mixture gas in the combustion chamber, a high maximum combustion pressure, maximum heat release rate and maximum pressure rise rate, a short combustion duration, and a high thermal efficiency. When the nozzle located in long axis vertex, the stability and continuity of combustion was better than the other two positions. The peak combustion pressure of the best injection advance angle was the highest. Under the optimal injection advance angle and with the other conditions unchanged, the maximum combustion pressure and maximum heat release rate appeared to reduce when changed the injection duration, but the impact was not significant. The combustion characteristics were still satisfactory, and the peak combustion pressure could reach to 6MPa above.

Abstract:In order to improve character of combustion of CNG engine, basing on type 6105 turbine charge CNG engine, the air flow in the cylinder and its combustion characteristic affected by different combustion chamber’s shape were simulated numerically. The result shows that the shape of combustion chamber plays an important role in the squish formation and combustion process. The contracted cave type combustion shape (chamber C) had much stronger squish and longer term period lasting compared with the others. The flame propagation velocity could be increased and the best combustion performance could be got. But the thermal load near igniter plug and the mass fraction of NOx produced during combustion in chamber C was higher. On the contrary, open cave type combustion (chamber B) had much weaker squish and slower flame propagation velocity. The worst combustion performance would be got. The situation of air flow in the cylinder and its combustion performance of vertical cave type combustion shape (chamber A) was between chamber C’s and chamber B’s. The suitable flame propagation velocity and good combustion performance could be got. And the thermal load near igniter plug and the mass fraction of NOx produced during combustion could be reduced. It was a suitable combustion chamber for CNG engine.

Abstract:A large-flow-rate electro-hydraulic control valve was designed by adopting pressure difference feedback rather than displacement feedback, the results of which was cost savings. Elliptical oil ports were designed to reduce the length and mass of the spool to improve the system response speed. For the fact that the response speed of hydraulic valve is affected by the throttling window, a system requiring large flow rate usually adopts large throttling window while a system requiring small flow rate usually adopts small throttling window. However, when the load of a system changes and leads to the change of the system flow rate demand, there is a trade-off between the system stability and speed. Mathematical model of the designed hydraulic control valve was established and simulation results showed that the adoption of composite throttling window could satisfy the demand of speediness in the case of large-flow-rate and the demand of stability in the case of small-flow-rate. And the maximum flow-rate and cut-off frequency of the valve was proved to be 417L/min and 73Hz. A prototype was manufactured and applied to hydraulic impulse testing systems for hose test, the result of which further verified the advantages of the hydraulic control valve.

Abstract:The forging manipulator was one of the important equipments in the automatic forging job. In order to design the 20T hydraulic forging manipulator with the performance characteristics of overload, high positioning accuracy and large inertia, the hydraulic control systems for the actuating mechanism of forging manipulator were designed. The hydraulic control systems consisted of driving system, clamp rotation system, parallel lifting system, horizontal buffer system, clamping system and lateral swing system. Mathematical models of manipulator’s key control system (driving system and clamp rotation system) were improved. Based on Matlab／Simulink and AMESim co-simulation technology, simulation and analysis on the dynamic characteristics of driving system and clamp rotation system with fuzzy PID control algorithm were given. The experiments were taken to verify the system performance, and the results showed that the designs of the hydraulic system circuits were reasonable. The accuracy and rapidity of the forging manipulator control system were achieved. The real-time response and robust performance of the driving system and clamp rotation system with fuzzy control strategy are strong and stable.

Abstract:Generally, the gear parameters of planetary vehicle transmission are got by the empirical design method. Some gears are damaged early because of low strength, as well as big structure size because of high strength in use. In this paper, the equal strength and minimum volume of the gear box planetary gears were regarded as optimization objective, and the assemble conditions were thought of optimization constraint. The gear parameters were obtained after calculation. Then planetary gears were analyzed by using ROMAX and the maximum of fatigue stress and fatigue life was obtained. The simulation and experiment result shows that some weak strength gears are enhanced and the whole strength is increased. The maximum gear contact stress is reduced from 1118MPa to 932MPa. The stress of all gears is more balanced and the difference of contact stress is decreased from 368MPa to 193MPa.The difference of gears figure life is shrunk from 157702h to 91588h compared to the conventional design gear life. The overall volume is reduced by 8.38%. The result is consistent with the optimization target.

Abstract:The detection, characterization, and matching of various 3-D features from visual observations is important for a large variety of applications such as modeling, tracking, recognition or indexing. The existing methods detect features by using either photometric information available with geometric information available with 3-D surfaces. To deal with the low retrieval accuracy problem in complex situation of 3-D objects retrieval, such as 3-D objects rotation and brightness changing, and a 3-D objects retrieval method was proposed. The Harris operator was extended the use of 3-D objects, and an adaptive technique was proposed to determine the neighborhood of a vertex. Then the significant interest points were chosen with the Harris response function value. To construct the global shape features distance histogram of 3-D objects with interest points, the distance histogram was used as the 3-D shape descriptor for 3-D object retrieval. Extensive experimental results demonstrated that the proposed method was robust to affine transformations and distortion transformation such as noise addition. Moreover, the distribution of interest points on the surface of an object remains similar in transformed objects, which is a desirable behavior in applications such as shape matching and object registration.